This is a magnet applicator tool set. It has a shaft/piston and interchangeable heads for different magnet sizes. 

The file includes two different colors for the heads to make sure you get the right polarity when inserting magnets. The piston is quite sturdy and it is ok to knock on it with a hammer or mallet, it is kind of the point. The magnet in the applicator sticks out slightly to ensure that the applicator does not hit the model when you try to insert magnets into it. All heads have the magnet dimensions written on them. The first few times you screw on a head you might have to force it slightly, but once screwed on it should be a tight fit and come on and off easily.

When inserting magnets into your models it is important that you get the right polarity. If you insert magnets with the same polarity into pieces that are supposed to stick together then they will repel instead. This tool and magnet heads makes getting the right polarity a breeze.

This applicator is for round magnets with the following dimensions (diameter on rows and depths in columns): 

Assembly instructions:

1. Insert a magnet into your black head.
2. Use the black head to insert magnets into the white heads. 
3. Use a white head to insert all magnets into the black heads.

Make sure you do not insert a magnet with the wrong polarity into a head. Using the head of one color to insert the magnet into the heads of the other color guarantees that the magnets have the right polarity!

Use instructions:

When working on a piece, a magnet inserted with a black head will always stick to a magnet inserted with a white head and vice versa. Two magnets inserted with a black head will repel, as will two magnets inserted with a white head.

Say you have a model with a body, two arms and two legs and you want to be able to attach the arms and legs to the body.

1. Insert all magnets on the body with the black head.
2. Insert all magnets on the arms and legs with the white head.
3. Arms and legs can now be attached anywhere on the body.

If instead you want the arms to only be able to attach where arms should go, and legs where legs should go:

1. Insert the magnets on the body, where arms should go with a black head.
2. Insert the magnets on the arms with a white head.
3. Insert the magnets where legs should go with a white head.
4. Insert the magnets on the legs with a black head. 
5. Now arms can only go where arms should go and legs can only go where legs should go.

Tips and tricks:

By combining multiple magnets in a pattern you can easily make parts that only go in a direction they are supposed to go. Say two magnets inserted with a black head and one with a white head, in a triangle, can only attach to another part with two inserted with a white head and one inserted with a black head, in a similiar triangular pattern. This way you can make parts that snaps into orientation or only attaches at some points with ease.